package com.kaifamiao.demo.d0820;

import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.Set;
import java.util.TreeSet;

public class Demo04 {

    public static void main(String[] args) {
        Set set = new HashSet();

//        TreeSet
//        LinkedHashSet


        set.add("a");
        set.add("a");


        for (Object obj : set){
            System.out.println(obj);
        }

    }
}
